Cholesteric Resin Display Medium for Authenticity Identification

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Solution Overview

Problem

The production of cholesteric resin layers for authenticity identification is challenging due to the difficulty in orienting and curing cholesteric liquid crystal compounds, leading to insufficient selective reflection function, reduced design flexibility, and ease of duplication.

Innovation Solution

A display medium with a droplet-cured product containing a cholesteric resin and metal particles, where the droplet-cured product has a half-width of the selective reflection band greater than 100 nm, is used, allowing for easier production and higher design flexibility by adjusting the color tone through temperature and light irradiation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cholesteric liquid crystal compound is oriented and cured to form cholesteric resin layer, then selective reflection function is achieved, but production difficulty increases and design flexibility decreases

Engineering Contradiction:
Improveselective reflection functionVSAvoidproduction difficulty
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the molecular helical pitch parameter of the cholesteric liquid crystal compound to control the color tone and selective reflection characteristics. By adjusting the helical pitch through chemical composition modification rather than physical orientation control, the production process is simplified while maintaining the selective reflection function.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent incorporates the cholesteric liquid crystal compound and chiral dopant in the initial layer formation stage, establishing the helical structure before curing. This preliminary arrangement of molecular structure eliminates the need for subsequent complex orientation adjustments, reducing production difficulty while preserving optical properties.

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If cholesteric resin flakes are used for printing, then design flexibility improves, but selective reflection function becomes insufficient and surface smoothness decreases

Engineering Contradiction:
Improvedesign flexibilityVSAvoidselective reflection function
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent creates a composite coating material by dissolving cholesteric liquid crystal compounds and chiral dopants in a solvent to form a homogeneous solution. This composite approach allows the material to be applied as a uniform layer that maintains strong selective reflection function while enabling flexible design through controlled drying and curing processes.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent enables local control of optical properties by adjusting the concentration of cholesteric liquid crystal compound and chiral dopant in different regions of the coating solution. This allows different color tones and reflection characteristics to be achieved in different areas, providing design flexibility while maintaining sufficient selective reflection function in each local region.

Inventive Principle:
Principle #3Local quality

3Reliability

If flake particle diameter is increased to improve selective reflection function, then surface smoothness and design flexibility deteriorate

Engineering Contradiction:
Improveselective reflection functionVSAvoidsurface smoothness
Core Design Contradiction:
ReliabilityVSShape

Solution Approach 1:

The patent replaces the mechanical flake structure with a molecular-level cholesteric liquid crystal solution. Instead of relying on physical flake particles that create surface irregularities, the optical function is achieved through the molecular helical structure of the liquid crystal compounds, which provides smooth surface characteristics while maintaining selective reflection capability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Manufacturing precision

If cholesteric liquid crystal compound orientation is adjusted to achieve desired color tone, then color accuracy improves, but production complexity increases

Engineering Contradiction:
Improvecolor tone accuracyVSAvoidproduction complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent achieves precise color tone control by modifying the chemical composition parameters - specifically the ratio of cholesteric liquid crystal compound to chiral dopant and the molecular helical pitch. This chemical parameter adjustment approach is simpler and more precise than physical orientation control methods, as it directly determines the reflection wavelength through the helical structure period.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The display medium provides enhanced authenticity identification with improved design flexibility and resistance to duplication, while maintaining a wide selective reflection band for effective authenticity verification.

Implementation Method 1

a display layer that reflects only specific polarized light and allow polarized light other than the foregoing to pass therethrough... a layer of the material containing the cholesteric liquid crystal compound... to exhibit a cholesteric liquid crystal phase

Methodology Applied
Scientific EffectCholesteric liquid crystal phase: Cholesteric Liquid Crystal

Implementation Method 2

to express a selective reflection function for circularly polarized light (a function of allowing to pass therethrough one type of circularly polarized light that is either one of clockwise circularly polarized light and counterclockwise circularly polarized light and reflecting a part or all of the other type of the circularly polarized light)

Methodology Applied
Scientific EffectSelective reflection function: Reflection

Implementation Method 3

the droplet-cured product contains a resin having cholesteric regularity... the display layer further contains a metal particle and a half width of a selective reflection band within the visible wavelength region of the droplet-cured product is greater than 100 nm

Methodology Applied
Scientific EffectCholesteric regularity: Cholesteric Liquid Crystal

Implementation Method 4

the step (3) includes light irradiation of the liquid crystal material... curing the liquid crystal material in the dispersion liquid while in a state of exhibiting the desired color tone

Methodology Applied
Scientific EffectLight irradiation curing: Photopolymerisation

Implementation Method 5

adjusting a color tone of the liquid crystal material in the droplets to a desired color tone... a subsequent heating step

Methodology Applied
Scientific EffectThermal effect on liquid crystal phase: Thermal Expansion

Data Source

PatentEP3502755B1Display medium for assessment and method for manufacturing same
Publication Date: 2024.07.31 ZEON CORP
  • EP3502755B1 patent drawingFigure 1~2
  • EP3502755B1 patent drawingFigure 3~4
  • EP3502755B1 patent drawing

AI summary

A display medium including a display layer for authenticity identification, wherein the display layer contains a droplet-cured product, and the droplet-cured product contains a resin having cholesteric regularity. The droplet-cured product preferably contains a cured product of a liquid crystal material containing a cholesteric liquid crystal compound. The display layer is preferably a cured product of a coating material containing the droplet-cured product. The display layer may contain plural types of droplet-cured products exhibiting different color tones as the droplet-cured product. The display layer may further contain a metal particle.